Absorption refrigeration apparatus



Oct. 13, 1942. F. R. BIICHOWSKY ABSORPTION REFRIGERATION APPARATUS Filed July 28, 1959 3 Coo/fag Wafer INVEN'IOR Franc/Is 516601039 1 Y I Patented (Pct. 13, 1 942 UNITED STATES PATENT oi-"rice 2,298,924 ABSORPTION, REFRIGERATION APPARATUS Francis R. Bichowsky, Ann Arbor, Mich. Application July as, 1939, Serial n. 286,989 16 Claimskci. 62-5) This invention relates to absorption refrigeration apparatus of the vacuum class.

An object of the invention is to provid-e'a sim ple, inexpensive, fully automatic control system for vacuum absorption refrigerators. Another object is to provide an absorption refrigerating system of rugged construction which will permit continuous trouble-free operation.

The invention may be explained with reference to the accompanying drawing, which illustrates diagrammatically a preferred embodiment ofthe invention.

The refrigeration effect is obtained in an evaporator I, into which water or other refrigerant liquid to be cooled enters through sprays 2. A portion of the liquid being sprayed evaporates, thereby chilling the remaining refrigerant to such an extent that it may again be used to supply external cooling, being withdrawn for this purpose through the pump 3. The refrigerant vapors formed in the evaporator escape through a tube 4 into an absorbing chamber 5 wherein they dissolve in an absorbent liquid which is supplied through inlets G'and trickles down the outside of a finned coil I. This coil is supplied internally-with cooling water, which entersfrom a water line 8 controlled by a valve 9, and leaves through a pipe Ill. The absorbent liquid, after trickling down the coil 1, is withdrawn from the chamber 5 by a pump H and is recirculated to the absorber inlets 6 through a line |2. The absorber 5 and evaporator I, being in open commu- .nication, are maintained at the.same reduced pressure, e. g. 2 to 3 millimeters of mercury absolute, by a vacuum pump l3, this pressure being indicated by a manometer l4.

Inasmuch as the absorbing liquid being recirculated through the chamber 5 tends to become diluted by the dissolving vapors of the refrigerant, a small proportion of the liquid is withdrawn continuously from the line |2' through a smaller line I5 and led to regenerator or boiler .IB which is fired by'a gas burner |'I controlled by a gas valve l8. In this regenerator refrigerant is vaporized or,.boiled out of the absorbent liquid, which, thus concentrated, returns to the absorber-5 through a leg I9. The refrigerant vapors. liberated in the regenerator l6 ascend through a tube 20 into a condenser 2|, in which they become liquefied by contact with the coil 22 through which cpoling water from the line I0 is being circulated to waste. The condensed refrigerant formed on the coil 22 drips to the bottom of the condenser 2| and then returns to the evaporator into the evaporator and absorber 5, throughthe legs 23 and Is, as will be explained.

In order to allow successful continuous opera- .tion of the apparatus described, it is essential that adequate means be provided for maintaining constant the pressure-differential between the regenerator-condenser system and the evaporator-absorber system. Thus,suitable valves may vbe inserted in the'connecting' lines I9 and 23.

Preferably, however, the evaporator I and absorber 5 are disposed higher than the regenerator I6 and condenser 2|, as illustrated, so that the pipes l9 and 23 in effect form legs of such height that the hydrostatic pressure therein is just equivalent to the pressure-differential it is desired to -maintain. Since the refrigerant in the leg 23 and theconcentrated absorbent in the leg IS in general do not have the same density, in order to insure that the hydrostatic pressures existing in the two legs are equal, it is necessary that the ratio of the heights (hydrostatic heads) of the legs l9 and 23 be inversely proportional to the ratio of the densities of the concentrated absorbent and the refriger nt. These heights are fixed at the required magnitude and ratio when the apparatus is first constructed, and thereafter in continuous operation it is necessary only to hold the concentration of the absorbent at the proper density, by means hereinafter explained.

. The operation of the apparatus is greatly improved by automatically maintaining a fixed pressure in the absorber 5 and evaporator In the apparatus illustrated, the pressure is controlled by the closed U-tube mercury manometer I4. This manometer is provided with a sealedin terminal 24 adapted to make electrical connection with the mercury at all times, and two sealed-in actuating contacts 25 and 26.. The contact 25 is electrically connected to the valve 9 controlling the flow of cooling water to the coil 1. The contact 26 is connected to the vacuum pump l3. In operation, when the pressure in the chamber 5 increases to such an extent that the mercury in the manometer rises to meet the contact 25, the electrical circuit is'energized, and the valve 9 opens, supplying cooling water to the coil 1. This water cools the absorbent. liquid flowing over the coil, and thereby lowers the pres- I through a leg 23. The regenerator I5 and its 55 sure in the chamber 5. Now, when the pressure falls to the point that the mercury in the manometer no longer touches the contact 25, the electrical circuit is no longer energized, and the valve 9 closes again. By this means a close regulation of the pressure in the chambers l and is attained. The apparatus operates smoothly under varying cooling loads, and there is no danger that the refrigerant will itself freeze. If, by some chance, the pressure in the absorber 5 should rise to a marked extent, the mercury in the manometer 14 may reach the contact 26, thus completing the circuit actuating the vacuum pump l3, which then reduces the pressure to the desired value In ordinary operation, adequate pressure regulation is attained merely by the automatic control of the cooling water valve 9. The vacuum pump serves only to purge the system of any air which may leak in. If a perfectly vacuum-tight system is constructed, the pump I3 is notrequired. The temperature of the refrigerant in the evaporator I may be adjusted to any desired value by suitably setting the position of the contact 25 in th manometer.

It will be understood that the U-tube manometer I4 is merely one form of pressure-responsive means which may be used to control the valve 9, and that any form of pressure-stat may be used.

.In fact, since the boiling point of the refrigerant in theevaporator I is a function of the applied pressure, pressure control may be obtained by replacing the manometer- M with a thermostat in contact with the liquid in the chamber I.

As her'einbefore stated, in order to achieve satisfactory operation and to insure that the hydrostatic pressures in the legs [9 and 23 remain equal throughout operation of the process, it is desirable to maintain the absorbent liquid in the regenerator It at a constant concentration. Since at constant pressure the boiling Point of a solution is a function of its concentration, the desired control may be obtained by placing a thermostat 21 in the regenerator l6,

' this thermostat being adapted to actuate the valve 18 controlling the heat supply to the regenerator. Now, if the solution in the regenerator becomes too dilute. its boiling point falls; this change in temperature affects the thermostat 21, which in turn causes the valve l8 to open wider, supplying more heat to the regenerator, thus concentrating the solution. In practice, the thermostat 21 also operates so that the amount of heat'introduced into the system at the regenerator I6 is proportional to theamount of refrigerant evaporated in the chamber It Hence, the entire system operates at maximum fuel economy. .The thermostat 21, may, although less satisfactorily, be replaced by any other device sensitive to'theconcentration of the absorbent in the regenerator.

While in a preferred form of the invention, the apparatus will be operated using water as the refrigerant and a hygroscopic solution as the absorbent liquid, it will be appreciated that the apparatus is also operable with other refrigerants and absorbents.

It is to be understood that the foregoing dis.-

cussion is illustrative rather than strictly limitative, and that the invention is co-extensive in scope with the following claims.

I claim:

1. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, and a regenerator for reconcentrating the absorbent: the combination of means for maintaining a constant pressure-differential between the absorber and the regenerator; means responsive to and adapted to control the pressure in the absorber; and means responsive to and adapted to control the concentration of the absorbent in the regenerator.

2. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a cooler for the absorber, a regenerator for reconcentrating the absorbent, and a heater for the'regenerator: the combination of means for maintaining a constant pressure-differential between the absorber and the regenerator; means responsive to the pressure in the absorber and adapted to control the cooler; and means responsive to the temperature in the regenerator and adapted to control the heater.

3. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a water-cooled coil in the absorber, a regenerator for reconcentrating the absorbent, and a heater for the re generator: the combination of means for maintaining a constant pressure-differential betweenthe absorber and the regenerator; a pressurestat in the absorber adapted to control the flow of cooling water in the absorber coil; and a thermostat in the regenerator adapted to control the heater.

4. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, and a regenerator for reconcentrating the absorbent: the combination of means for maintaining a. substantially constant pressure-differential between the absorber and the regenerator, and between the evaporator and the condenser; means responsive to and adapted to control the pressure in the absorber; and means responsive to and adapted to control the concentration of the adapted to control the cooler; and means re-- sponsive to the temperature in the regenerator and adapted to control the heater.

6. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a water-cooled coil in the absorber, a regenerator for reconcentrating theabsorbent, and a heater for the regenerator: the combination of means for maintaining a substantially constant pressure-differential between the absorber and the regenerator and between the evaporator and the condenser; a pressure-stat in the absorber adapted to control the flow of cooling water in the absorber coil; and a thermostat in the regenerator adapted to control the heater.

7. In a. vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a cooler for the absorber, a vacuum pump adapted to exhaust the absorber, "a regenerator for reconcentrating the absorbent, and a heater for the regenerator: the combination-of means for maintaining a con,

stant pressure-differential between the absorber and the regenerator; means responsive to the pressure in the absorber and adapted to control the cooler and the vacuum pump so as to maintain a constant pressure in the absorber; and means responsive to and adapted to control the concentration of the absorbent in the regenerator.

8. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a cooler for the absorber, a regenerator for reconcentrating the absorbent, and a heater for the regenerator: the combination of means for maintaining a substantially constant pressure-differential between the absorber and the regenerator; means responsive are inversely proportional to the densities of the the absorber, a vacuum absorber and the regenerator; means responsive to the pressure in the absorber and adapted to control the cooler so as to maintain a substantially constant pressure in the absorber; and means responsive to the temperature in the reas to maintain the absorbent at a substantially constant concentration.

10. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a watercooled coil in the absorber, a regenerator for reconcentrating the absorbent, and a heater for the regenerator: the combination of means for maintaining a substantially constant pressure-differential between the absorber and the regenerator; a pressure-stat adapted to increase the flow of cooling water in the water-cooled coil when the pressure in the absorber exceeds a predetermined value and to decrease the flow of cooling water in the water-cooled coil when the pressurefalls' said liquids; and a thermostat in the regenerator adapted to control the heater so as to maintain the absorbent at a substantially constant concentration.

12. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a cooler for pump adapted to exhaust the absorber, a regenerator for reconcentrating the absorbent, and a heater for the regenerator: the combination of means formaintaining a constant pressure-differential between "the absorber and the regenerator; means responsive to the pressure in the absorber and adapted to control the cooler and the vacuum pump 50 as to maintain a constant pressure in the absorber; and means responsive to the temperature in the regenerator and adapted to control the heater so as to maintain the absorbent at a canstant con centration.

13. In a vacuum absorption refrigeration system comprising an absorber for dissolving the vapors of a refrigerant in an absorbent, a watercooled coil in the absorber, a vacuum pump adaptedto'exhaust the absorber, a regenerator for reconcentrating the absorbent, and a heater for the regenerator: the combination of means for maintaining a constant pressure-diflerential between the absorber and the regenerator; a pressure-stat adapted to actuate the vacuum pump when the pressure in the absorber exceeds generator and adapted to control the heater so frigerant; an absorber in open communication with the evaporator for dissolving refrigerant vapors; a water-cooled coil in said absorber; a regenerator for freeing the absorbent of dissolved refrigerant; a heater for the regenerator; a condenser for refrigerant vapors in open communication with the regenerator; means for maintaining a substantially constant pressure-. differential between the regenerator-condenser system and the evaporator-absorber system, the

former being at the higher pressure, said means comprising a leg for carrying absorbent from the regenerator to the absorber and a second leg for carrying refrigerant from the condenser to the evaporator, the evaporator, absorber, condenser, and regenerator being so disposed that the said legs are of such relative heights that the hydrostatic heads of the liquids flowing therein a predetermined value and to decrease the flow of cooling water in the absorber coil when the pressure falls below apredetermined value; and means responsive to the'temp'erature in the regenerator and adapted to control the heater so as to maintain the absorbent-at a constant concentration.

14; In avacuum absorption refrigeration sys tem comprising a refrigerant and an absorbent, the combination of an evaporator for the refrigerant; an absorber in open communication with the evaporator for dissolving refrigerant vapors; means for maintaining the evaporator and absorber at reduced pressure; a regenerator vfor freeing the absorbent of dissolved refrigerant; a condenser for refrigerant vapors in open communication with the regenerator; and means for maintaining a constant pressure-differential betweenthe regenerator-condenser system and the evaporator-absorber system, the former being at a somewhat higher pressure, said means comprising a leg for carrying absorbent from the regenerator to the absorber and a second leg for carrying refrigerant from the condenser to the evaporator, the evaporator, absorber, condenser,

and regenerator being so disposed that the heads of the liquids flowing therein are inversely proportional to the densities of the said liquids.

15. In a vacuum absorption refrigeration system comprising a refrigerant and an absorbent, the combination of: an evaporator for the refrigerant; an absorber in open communication with the evaporator for dissolving refrigerant vapors; a' water-cooled coil in said absorber; a vacuum pump for exhausting the absorber and evaporator; a regenerator for freeing the absorbent of dissolved refrigerant; a heater for the regenerator; a condenser for refrigerant vapors in open communication with the regenerator; means for maintaining a small constant pressure-difierential between the regenerator-condenser system and the evaporator-absorber system, the former being at the higher pressure,

said means comprising a leg for carrying absorbent from the regenerator to the absorber and a second leg for carrying refrigerant from the condenser to the evaporator, the evaporator, absorber, condenser, and regenerator being so disposed that the said legs are of such relative heights that the hydrostatic heads of the liquids flowing therein are inversely proportional to the densities of the said liquids; a pressure-stat in the absorber adapted to actuate the vacuum pump when the pressure in the absorberlexceeds a predetermined value and to decrease he flow of cooling water in the absorber coil when the pressure falls below a predetermined value; and a thermostat in the regenerator adapted to control the heater so as to maintain the absorbent at a constant concentration.

16. In a vacuum absorption refrigeration system comprising an evaporator for the refrigerant, an absorber in open communication with the evaporator for dissolving the vapors of the re,- frigerant in an absorbent, a cooler for the absorber, a regenerator for reconcentrating the absorbent, and the heater for the regenerator, a condenser in open communication with the regenerator, the combination of: means responsive to a variation in pressure-differential between the absorber andthe regenerator and adapted to maintain the pressure-diflerential, within predetermined limits which comprises relatively so disposing the condenser, the evaporator, the absorber, and the regenerator that a leg for transferring absorbent from the regenerator to the absorber and a leg for transferring refrigerant from the condenser to the evaporator are of such relative heights that the hydrostatic heads of the liquids flowing therein are inversely proportional to the densities of said liquids.

FRANCIS R. BICHOWSKY. 

